The present invention relates generally to a heating system for vehicles having an internal combustion engine and more particularly to a heating system comprising means for introducing heated air into the interior of the vehicle.
Various types of heating systems for heating vehicle passenger compartments are known, and in some cases such heating systems have the capability of heating the vehicle interior independently of the operating condition of the vehicle engine. That is, in many cases known heating systems are capable of providing heat to the vehicle passenger compartment when the engine is not running or is operating in a cold condition.
Such heating systems are generally considered as supplemental heat sources inasmuch as they can be operated independently of or in addition to the heating system of the vehicle engine. Generally, such known heaters consist of a combustion chamber capable of burning therein a liquid fuel for generating the necessary heat energy. These heaters usually include means for introducing combustion air and ignition means for igniting the fuel mixtures. There may also be provided a heat exchanger which surrounds the combustion chamber of such a heating system in order to heat the air which is supplied to the vehicle interior. Usually a heated air blower is provided for blowing or drawing the heated air through conduit means for delivery to the vehicle passenger compartment.
In some known heating systems, the heating units are operated by means of the engine exhaust gases. In such systems, the heating process is accomplished without utilization of a combustion chamber, but rather by utilizing the vehicle exhaust pipe as a heat source in place of a combustion chamber. A heat exchanger may be provided through which the air to be heated flows in heat exchange relationshiop with a portion of the engine exhaust pipe.
Although systems such as those previously mentioned may provide many advantages, it will be seen that several disadvantages nevertheless arise. In a system where a separate combustion source must be provided, there is required provision of a liquid fuel, such as gasoline or diesel oil, in addition to the fuel which must be provided for engine operation. Furthermore, such a heating system must provide a separate exhaust system of its own.
In heating systems operated by the exhaust gases of the vehicle, disadvantages arise due to the requirement of expensive safety measures. In such systems, there must be provided assurance that no exhaust gases will reach the air heating system and, consequently, the interior of the vehicle.
In heating technologies normally involving applications other than vehicles, for example, home or living space heating applications, there is known the principle of utilizing heat storage means wherein stored heat may be conserved for utilization when desired. Such heating systems may employ a heat storage medium such as transformer oil or ceramic compounds which are heated preferably by means of electrical energy with the stored heat being tapped as needed by means of a blower or other similar device. It is known that liquids, such as transformer oil, are capable of storing heat. Furthermore, in nuclear energy plants, for example, liquid sodium is used as a heat transfer medium. It has been found that certain principles and knowledge which normally find application in living space heating technology and which involve use of heat storage devices, may be developed to provide a heating system for a vehicle having an internal combustion engine.
The present invention is directed toward adapting such principles to use in vehicle heating applications. By means of the present invention, a heating system for a vehicle having an internal combustion engine may be developed which functions by utilization of a heat storage principle deriving heat energy by utilizing the vehicle exhaust gases as a heat source. With the present invention, certain advantages of known heating technologies may be provide in vehicle heating applications while avoiding many of the disadvantages of known vehicle heating systems.